Rain, storms, wind, and a cooldown: Big weather changes for NJ

Our extended stretch of pleasant, mild, mostly sunny weather is about to come to an abrupt end.

(Maps: College of DuPage Meteorology)

Here are your weather headlines for Monday, October 23, 2017...

Monday: The Grand Finale

By my count, 18 of the last 19 days have featured above-normal temperatures in New Jersey. Most of those days were cloud-free, rain-free, and drop dead gorgeous. That streak of pleasant weather will be threatened by a cold front, which promises to make Tuesday a very active weather day for the entire Garden State.

NAM model simulated radar forecast product, showing the steady rain should hold off until the daytime hours on Tuesday. (College of DuPage Meteorology)

Let's start with Monday, which looks mostly quiet. Scattered patches of dense fog have formed Monday morning, leading to visibilities below a half-mile in a few spots. Skies will remain mostly cloudy (at least) throughout the day, and the latest model suite even suggests a few sprinkles, spritzes, and areas of mist for Monday too. You'll feel the humidity in the air by Monday afternoon, with a slowly strengthening breeze too. High temperatures should still hover about 10 degrees above normal for late October, in the lower to (maybe) mid 70s.

Monday night looks cloudy, breezy, humid, and pretty warm. Low temperatures are forecast to fall to about 63 to 70 degrees — much more typical of the summer than the fall. A shower will be possible at any time, especially in the pre-dawn hours early Tuesday morning.

Tuesday: Wet and Windy

Tuesday will not be a pleasant weather day. Period. The culprit will be a slow-moving cold front, which will serve as a highway for atmospheric shortwaves (mini storm systems) throughout the day. Depending on the speed of the front and the intensity of the disturbances, we could be dealing with some big rainfall totals, alongside other weather impacts.

The NAM total rainfall model forecast is the high outlier, with an area of 3 to 6 inches of rain over NJ. (College of DuPage Meteorology)

--RAIN: For several days, models have shown good consensus toward a widespread inch of rain between late Monday night and early Wednesday morning. Considering our recent dearth of rainfall — 47.5 percent of the state is now officially classified as "abnormally dry," we could use some healthy rainfall. However, this morning's NAM model in particular slows the front considerably, putting an isolated swath of 3 to 6 inches of rain over part of New Jersey. That's a little too much rain to come all at once, leading to potential flooding concerns.

--STORMS: Given the warmth and humidity, marginal instability in the atmosphere will probably be sufficient to spawn a few embedded thunderstorms. Cloud-to-ground lightning is always potentially dangerous, and we could potentially see some damaging wind and hail too. The Storm Prediction Center has placed all of New Jersey in a "Slight Risk" for Tuesday, indicating a 15 percent chance of significant severe weather.

--WIND: Aside from the wet weather, Tuesday is going to be a windy day too. Sustained winds of 15 to 25 mph are likely, with gusts over 40 mph possible (especially along the coast).

--TIMING: Showers could arrive as early as 11 p.m. Monday, but the heaviest rain should hold off until 5 a.m. Tuesday or later. The heaviest rain will fall during the day on Tuesday, possibly extending to as late as 5 a.m. Wednesday morning. The wind will follow the same timeline, with the strongest gusts between early Tuesday morning and early Wednesday morning.

Wednesday and Beyond: Autumn Returns

As showers and clouds depart Wednesday morning, skies should clear as humidity drops rapidly. We should enjoy solid breaks of sunshine by lunchtime Wednesday. Of course, behind the cold front will come cooler air too. Highs on Wednesday will be limited to the mid to upper 60s. (Still above normal, by the way.)

NAM model temperature forecast for Thursday morning, showing the return of 40s, making for a seasonably chilly start to the day. (College of DuPage Meteorology)

Thursday promises to be even cooler, despite mostly sunny skies. High temperatures will be much more seasonable and autumnal, topping out between about 60 and 65 degrees. Morning lows will primarily be in the 40s.

More 60s are forecast for Friday and Saturday, before another cold front pushes temperatures downward once again. Following a brief round of rain, Sunday's high temperatures may get stuck in the 50s. I'm still eyeing the morning of Monday 10/30 for New Jersey's first widespread (i.e. almost statewide) frost/freeze of the season.

Dan Zarrow is Chief Meteorologist for Townsquare Media New Jersey. Follow him on Facebook or Twitter for the latest forecast and realtime weather updates.